Effects of different growth periods on the quality of ‘118’ forage millet silage

To determine the optimal growth period of forage millet (Setaria italica) silage, a random block design was adopted in this study, using ‘118’ forage millet varieties as test varieties. They were harvested during the filling period, milk maturity period, and wax maturity period to prepare small package silage. After 60 days of anaerobic fermentation, the nutrient composition, fermentation quality, and microbial composition were compared. The result showed that: 1) As the growth period progressed, dry matter content in the silage gradually increased, while the crude protein content and soluble carbohydrate content showed a decreasing trend, and the soluble carbohydrate content in the milk maturity period was higher. 2) After 60 days, the number of lactic acid bacteria in silage increased, with the highest number being observed in the treatment group in the milk maturity period. There were a certain number of molds, yeasts, and general aerobic bacteria in each treatment group. 3) The pH value in different growth periods was relatively high and the lactic acid content was low, but the presence of butyric acid was not detected. 4) The membership function value method was used for comprehensive evaluation, and the evaluation results were in the order: milk maturity > dough stage > filling period. Although there were differences in silage quality at different growth stages, it did not reach the standard of high-quality silage. The addition of exogenous silage additives was an effective means to improve the silage quality of forage millet and reduce nutrient loss.